The AREA MODEL: Can one just use it willy-nilly?
Sure, computing 37 x 21 via the area model makes perfectly good sense and there is good place for this approach in early-grade maths. But surely you can’t use the area model in upper-grade algebra too? Afterall (3x+7)(2x+1) is fine if x=10 (it is still 37 x21), but what if x is a negative number as is allowed in algebra? You can’t have negative side lengths and negative areas in geometry!